A preferred tube removal practice for use in connection with maintenance operations for typical tube-type boilers involves cutting the boiler tube that is to be replaced at locations adjacent the boiler headers in which the tube is installed, removing the cut major tube length from within the boiler, and afterwards separately removing the two remaining tube ends mounted in the tube mounting bores of the boiler tube headers from within their tube mounting bores. The subsequent removal of the tube ends generally has involved the use of apparatus that is first clamped to the interior surface of nearby tubes or other tube ends installed in the same boiler tube header, and that is then subsequently actuated to machine a longitudinal gap or slit in the wall of tube end to be removed. Afterwards, and following apparatus removal, the candidate tube end is laterally compressed to close the machined longitudinal gap, and manually or otherwise withdrawn from installation within the boiler header tube mounting bore. The preferred practice of tube removal avoids the probable damage to the boiler header tube mounting bores that typically occurs when other methods of tube removal such as oxy-acetylene flame cutting or axial driving force separation are utilized, and thus effectively eliminates the probable need for subsequent header metal repair and header tube mounting bore redrilling and honing.
However, the known boiler tube machining apparatus has not been found to function optimumly in all instances, and particularly in cases where the tube interior diameter is not uniform throughout its length due to non-uniform mineral or oxide scale encrustation in the tube, or where adequate adjacent tubes or tube ends are not available for initial apparatus clamping. Accordingly, we have invented a novel apparatus that may be utilized to advantageously in-part effect the removal of boiler-tube ends from their mountings without causing damage to the co-operating boiler header tube mounting bores even in cases where significant non-uniformity of tube interior scaling exists or even if no adjacent boiler tubes or tube-ends are available for satisfactorily clamping the apparatus to the boiler header.
Other advantages and objectives of the invention will become apparent in the course of considering the detailed descriptions, drawings, and claims which follow.